The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
It is well known to the experts in the field that it is hard to obtain a sub-linear similarity search-operation over a large vector data set. Research results have been obtained on limited data sets such as time series data and face image data, etc. These results mainly focused on variations of statistical clustering analysis, such as: (a) “static” supporting vector analysis that divides the data set into a smaller number of clusters to facilitate the search operation; (b) “dynamic” tree structures to support a hierarchical search; and (c) perform cosine or wavelet transformation to select dominant coefficients that can be used to approximate the original data.